class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """ 
		:type nums: List[int]
		:rtype: None Do not return anything, modify nums in-place instead.
		"""
        if not nums:
            return 0
		# 两个指针i和j
        j = 0
        for i in range(len(nums)):
            # 当前元素!=0，就把其交换到左边，等于0的交换到右边
            if nums[i]:
                nums[j],nums[i] = nums[i],nums[j]
                j += 1

